Interesting idea, huh? An astable oscillator chip, with variable frequency, a push pull amp and a power FET/ IGBT. You can run flybacks and ignition coil too, just changing the timing cap on the oscillator. ELECTRIC SCHEMA

There are a few differences. For flybacks I prefer to run a MOSFET (IRFP460, 500 V @ 20 A) with an ultrafast diode across drain- source (RHRP15120, 1200 V @ 15 A), because they cope very well with the higher frequencies (up to and above 100 kHz). For ignition coil, is preferable to use an IGBT, for lower voltage drop and more current (I used BUP307, 1200 V @ 35 A) and a transient voltage supresor diode between drain and source (used 1.5 KE 440 CA, bidirectional). For flybacks is better to wind your own primary, with some insulated, thick wire, usually around 10 turns. I used an AC flyback. The timing capacitor (C) has different values depending what you are using. For flybacks I am using a 1 nF cap, as in the original schema. For ignition coil, the old schema used a 33 nF cap, but I like more to run a 100 nF cap, because it is featuring a larger range of BPS (from high frequency to a spark at a few seconds). The 6.8 nF cap across the FET/IGBT heats a lot, a 100 nF cap will work cooler. The TVS runs hot too at high frequencies and high voltages input.